Auto merge of #23896 - nox:layout-2020, r=SimonSapin

Remove most of the things in layout 2020

We keep mostly the query system. There is probably more to delete but
that's a good start I think.

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components/style/properties/longhands/inherited_text.mako.rs

@@ -196,7 +196,7 @@ ${helpers.predefined_type(
     spec="https://drafts.csswg.org/css-text/#propdef-white-space"
     servo_restyle_damage="rebuild_and_reflow"
 >
-    % if engine == "servo-2013":
+    % if engine in ["servo-2013", "servo-2020"]:
     impl SpecifiedValue {
         pub fn allow_wrap(&self) -> bool {
             match *self {